Neuropeptide Y (hereinafter referred to as NPY), a peptide consisting of 36 amino acids, was first isolated from porcine brain by Tatemoto et al. in 1982 [Nature, 296: 659 (1982)]. NPY is widely distributed in central nervous system and peripheral nervous system and plays various roles as one of the most abundant peptide in the nervous system. That is, NPY acts as an orexigenic substance in the central nervous system and markedly promotes fat accumulation via the mediation of the secretion of various hormones or the action of the nervous system. It is known that the continuous intracerebroventricular administration of NPY induces obesity and insulin resistance based on these actions (International Journal of Obesity, vol.19: 517 (1995); Endocrinology, vol.133: 1753(1993)). It is also known that NPY has central effects, such as depression, anxiety, schizophrenia, pain, dementia and the like (Drugs, vol. 52, 371(1996). Further, in the periphery, NPY coexists with norepinephrine in sympathetic ending and is involved in the tonicity of the sympathetic nervous system. It is known that peripheral administration of NPY causes vasoconstriction and enhances the activities of other vasoconstrictive substances such as norepinephrine (British Journal of Pharmacology, vol.95: 419 (1988)). It is also reported that NPY could participate in the development of cardiac hypertrophy as a result of the sympathic stimulation (Proceeding National Academic Science USA, Vol. 97, 1595(2000)).
On the other hand, it is reported that NPY is also involved in the secretory function of sexual hormones and growth hormone, sexual behavior and reproductive function, gastro-intestinal motility, bronchoconstriction, inflammation and alcohol preference (Life Science, vol. 55, 551(1994); The Journal of Allergy and Immunology, vol. 101, S345(1998); Nature, vol. 396, 366(1998)).
NPY has a variety of pharmacological effects which result from NPY binding to the NPY receptors. Other NPY related peptides, including peptide YY and pancreatic polypeptide also bind to the NPY receptors. It is known that these pharmacological effects are mediated by the action of, at least, five receptor subtypes with or without synergistic interactions. (Trends in Neuroscience, vol. 20, 294(1997)).
Y1: It is reported that the central effect mediated by NPY Y1 receptor includes the remarkable orexigenic effect (Endocrinology, vol. 137, 3177(1996); Endocrinology, vol. 141, 1011(2000)). Further, the Y1 receptor is reported to be involved in anxiety and pain (Nature, vol. 259, 528(1993); Brain Research, vol. 859, 361(2000)). In addition, the pressor effects mediated by the strong action of vasoconstriction in the periphery by NPY is also reported to be mediated by Y1 (FEBS Letters, vol. 362, 192(1995); Nature Medicine, vol. 4, 722(1998)).Y2: It is known that the inhibitory effect on the release of various neurotransmitters in the sympathetic nerve endings is mediated by the NPY Y2 receptor (British Journal of Pharmacology, vol. 102, 41(1991); Synapse, vol. 2, 299(1988)). In periphery, NPY causes constriction of blood vessel or vas deferens directly or via the control of release of various neurotransmitters (The Journal of Pharmacology and Experimental Therapeutics, vol. 261, 863(1992); British Journal of Pharmacology, vol. 100, 190(1990)). In addition, inhibition of lipolysis in adipose tissues is known (Endocrinology, vol. 131, 1970(1992)). Further, the inhibition of ion secretion in the gastrointestinal tract is reported (British Journal of Pharmacology, vol. 101 247(1990)).
On the other hand, the inhibitory effect on the central nervous system functions such as memory and anxiety is also reported (Brain Research, vol.503, 73(1989); Peptides, vol. 19, 359(1998)).
Y3: It is reported that NPY Y3 receptor is mainly located at brainstem and in the heart and is related to regulation of blood pressure and heart rate (The Journal of Pharmacology and Experimental Therapeutics, vol. 258, 633(1991); Peptides, vol. 11, 545(1990)). Further, it is known that the Y3 receptor is involved in the control of catecholamine secretion in adrenal gland ((The Journal of Pharmacology and Experimental Therapeutics, vol. 244, 468(1988); Life Science, vol. 50, PL7(1992)).Y4: NPY Y4 receptor has high affinity for pancreatic polypeptide. The related pharmacological effects reported to be mediated by the Y4 receptor include the inhibition of pancreatic secretion and the gastro-intestinal motility (Gastroenterology, vol.85, 1411(1983)). Further, it is reported that NPY enhances the secretion of the sexual hormone in the central nervous system (Endocrinology, vol. 140, 5171(1999)).Y5: The effect mediated by NPY Y5 receptor includes feeding stimulation and accumulation of fat (Nature, vol. 382, 168(1996)); American Journal of Physiology, vol. 277, R1428(1999)). It is reported that the NPY Y5 receptor also mediates some CNS effects, such as seizure and epilepsy, or pain and the morphine withdrawal symptoms (Natural Medicine, vol. 3, 761(1997); Proceeding Academic Science USA, vol. 96, 13518(1999); The Journal of Pharmacology and Experimental Therapetics, vol. 284, 633(1998)). In the periphery, the Y5 receptor is reported to be involved in diuresis and hypoglicemic effect caused by NPY (British Journal of Pharmacology, vol. 120, 1335(1998); Endocrinology, vol. 139, 3018(1998)). NPY is also reported to enhance cardiac hypertrophy as a result of the sympathic accentuation (Proceeding National Academic Science USA, Vol. 97, 1595(2000)).
The effects of NPY occur by binding to the NPY receptors in the central or peripheral nervous system. Therefore, the action of NPY can be prevented by blocking the binding to NPY receptors. Substances antagonize NPY binding to NPY receptors may be useful for the prophylaxis or treatment of various diseases related to NPY, such as cardiovascular disorders (for example hypertension, nephropathy, heart disease, vasospasm), central nervous system disorders (for example bulimia, depression, anxiety, seizure, epilepsy, dementia, pain, alcoholism, drug withdrawal), metabolic diseases (for example obesity, diabetes, hormone abnormality), sexual and reproductive dysfunction, gastro-intestinal motility disorder, respiratory disorder, inflammation or glaucoma and the like (Trends in Pharmacological Sciences, 15: 153(1994); Life Science,. 55, 551(1994); Drugs, vol. 52, 371(1996); The Journal of Allergy and Immunology, vol. 101, S345(1998); Nature, vol. 396, 366(1998); The Journal of Pharmacology and Experimental Therapeutics, vol.284, 633(1998); Trends in Pharmacological Science, vol. 20, 104(1999); Proceeding National Academic Science USA, vol. 97, 1595(2000)).
Recently, according to the investigation of the present inventors, it has been found that some kind of NPY receptor antagonist is useful in the prophylaxis or treatment of hypercholesterolemia, hyperlipidemia and arteriosclerosis [International application publication WO99/27965].